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SubjectRe: [PATCH v3 0/6] Handle update hardware queues and queue freeze more carefully
On Fri, Jul 30, 2021 at 11:49:07AM +0200, Daniel Wagner wrote:
> On Mon, Jul 26, 2021 at 07:27:04PM +0200, Daniel Wagner wrote:
> > FTR, I've tested the 'prior_ioq_cnt != nr_io_queues' case. In this
> > scenario the series works. Though in the case of 'prior_ioq_cnt ==
> > nr_io_queues' I see hanging I/Os.
>
> Back on starring on this issue. So the hanging I/Os happen in this path
> after a remote port has been disabled:

It turns out, the same happens with TCP as transport. I've got two
connection configured and block traffic on the target side with
iptables rules. This is what I see

nvme nvme16: creating 80 I/O queues.
nvme nvme16: mapped 80/0/0 default/read/poll queues.
nvme nvme16: new ctrl: NQN "nqn.2014-08.org.nvmexpress:NVMf:uuid:de63429f-50a4-4e03-ade6-0be27b75be77", addr 10.161.8.24:4420
nvme nvme17: creating 80 I/O queues.
nvme nvme17: mapped 80/0/0 default/read/poll queues.
nvme nvme17: new ctrl: NQN "nqn.2014-08.org.nvmexpress:NVMf:uuid:de63429f-50a4-4e03-ade6-0be27b75be77", addr 10.161.8.24:4421
nvme nvme17: starting error recovery
nvme nvme17: failed nvme_keep_alive_end_io error=10
nvme nvme17: Reconnecting in 10 seconds...
nvme nvme17: failed to connect socket: -110
nvme nvme17: Failed reconnect attempt 1
nvme nvme17: Reconnecting in 10 seconds...
nvme nvme17: failed to connect socket: -110
nvme nvme17: Failed reconnect attempt 2
nvme nvme17: Reconnecting in 10 seconds...
nvme nvme17: creating 80 I/O queues.
nvme nvme17: Successfully reconnected (3 attempt)

Call Trace:
__schedule+0x2d7/0x8f0
schedule+0x3c/0xa0
blk_queue_enter+0x106/0x1f0
? wait_woken+0x80/0x80
submit_bio_noacct+0x116/0x4b0
? submit_bio+0x4b/0x1a0
submit_bio+0x4b/0x1a0
__blkdev_direct_IO_simple+0x20c/0x350
? blkdev_iopoll+0x30/0x30
? blkdev_direct_IO+0x4a2/0x520
blkdev_direct_IO+0x4a2/0x520
? asm_sysvec_apic_timer_interrupt+0x12/0x20
? generic_file_read_iter+0x84/0x140
? __blkdev_direct_IO_simple+0x350/0x350
generic_file_read_iter+0x84/0x140
blkdev_read_iter+0x41/0x50
new_sync_read+0x118/0x1a0
vfs_read+0x15a/0x180
ksys_pread64+0x71/0x90
do_syscall_64+0x3c/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae

I think all transport handle the unfreezing incorrectly in the
recovering path. At least for TCP and FC I could test this. I don't have
and RDMA setup but this code looks suspiciously the same.. I think the
nvme_unfreeze() needs to be called always not just in the case where the
number of queues change.

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